Retroviral aspartyl proteases or retropepsins are single domain aspartyl proteases from retroviruses, retrotransposons, and badnaviruses (plant dsDNA viruses).

These proteases are generally part of a larger pol or gag polyprotein.

pol polyprotein undergoes specific enzymatic cleavage to yield the mature proteins.

Not all retroviral aspartyl proteases generated from pol are retropepsins in the strict sense.

Spumapepsin from foamy virus is divergent enough to get its own family, MEROPS A9.